with certainty
by bravevulnerability
Summary: 'It's probably later than what is appropriate for him to be showing up on her doorstep, the city-lit darkness of nightfall pressing in against her windows, the lingering taste of her mouth still on his tongue, and his hand still alive with a pain that laces through his knuckles.' An AU post-ep for 3x13, Knockdown.


**A/N: For S, thank you.**

* * *

The number of times he has seen Kate Beckett cry, he can count on one hand, but despite his lack of viewings to her rare displays of emotion, he knows from the second she opens her front door to him that she's been crying. Again. And it hurts him, causes his heart to ache in a way that he doesn't quite understand. Similar to how he feels when he witnesses his daughter in emotional turmoil, his mother, though, like Beckett, she has hardly allowed him to see that.

But it's different with Kate, different to see a woman who has the exterior of a warrior with glistening eyes and a quivering lip. It's worse.

"Hey, Castle," she greets him with that waning smile, a gentle crease tugging on her brow. "What are you doing here?"

It's probably later than what is appropriate for him to be showing up on her doorstep, the city-lit darkness of nightfall pressing in against her windows, the lingering taste of her mouth still on his tongue, and his hand still alive with a pain that laces through his knuckles. He should be at home with his family, icing his hand or trying to write, attempting a night of rest; he should probably be doing anything but showing up at her apartment so close to midnight.

"I - I wasn't sure you'd be awake," he stammers, lifting the small takeout bag in his hand. He always comes bearing gifts, flowers, food - arriving empty handed made this seem like it was more, more than two friends sharing company and conversation, and he can't afford to think like that right now. He needs to think of anything but the sound of her moan still echoing through his ears. "But I uh, I just couldn't… I've been a bit wired."

"After your throwdown with a sniper," she sighs, narrowing her eyes at him with soft reprimand. "I can't say I'm surprised."

"Yeah," he breathes out in relief. He'd been worried that she would close the door in his face despite the night they've had, tell him to go home and allow her a few hours' peace. But she seems to welcome his company, a barely visible hint of delight flickering through the moisture crowding her gaze. "And I'm sorry for just showing up like this, especially while Josh-"

"Africa, Rick," she reminds him, stepping aside and widening the entrance of the doorway for him. And had she just called him _Rick_? "Josh is still in Africa and even if he wasn't, I'd still let you in."

Calling him by his first name _and_ being nice to him. Oh yeah, he's officially concerned.

Beckett eases the door shut once Castle is inside, already migrating through the now familiar foyer to her kitchen, placing the takeout bag on the counter, listening to her lock the deadbolt. She's dressed down, much like she was earlier in the week when he was here, a loose t-shirt that exposes the cutting edge of her collarbone, the pale moon of her shoulder, black leggings in the place of jeans, bare feet instead of sneakers.

"When's he set to return?" Castle inquires, attempting to be polite, small talk and all that, but irritation flashes in Kate's eyes, a spark of gold amidst the amber as she scrapes a hand through her hair. But it isn't aimed at him.

"Next Friday, I think, but it doesn't matter anymore," she mutters, shuffling into the kitchen to join him, peering around the stovetop to see the contents he's withdrawing from the paper bag, but his hands have gone still.

"It doesn't?"

He watches her lips purse, the bottom being sucked into her mouth, falling victim to the gnaw of her teeth, deciding.

"We had a fight," she murmurs, avoiding the spear of his gaze on her, hiding behind the honey brown curtains of her hair. "You… you know how I get with her case, how obsessive I become, but Josh never - he never had any idea. I've been so sucked in this week, I completely ignored my phone unless it was the precinct or you." His heart skips even though it shouldn't. "And once I finally did call him back, I'd missed four days worth of calls and he wasn't happy. He doesn't think I'm capable of being what he'd hoped for."

"How could you not be?" Rick demands without thinking, but his blood boils in synchrony with the collapse of his heart at the look on her face, the shame. No one should make her look like that, no one should be allowed that right, that terrible power. "Kate, you - extraordinary, remember? You are extraordinary and if Josh can't see that-"

"He's right, Castle," she interrupts, her voice soft and her smile small, a wry, broken thing strung across her lips. "I'm… how can I ever be in a relationship, be there for someone, when my main focus is hunting down a dragon?"

His instinct is to drift towards her, offer comfort with the touch of his hand, but her arms are folded tightly across her chest, holding herself together by the looks of it, and he forces himself to remain rooted to the spot.

"Kate-"

"Why don't you finish unloading… what did you even bring?" she asks, inhaling through her nose, her chest rising with the deep breath, steadying the riot of emotion in her eyes and forcing the corners of her mouth to quirk.

"Just a midnight snack," he decides to indulge her, just for now, just until she's ready to say more. "Some comfort food. I wasn't sure if you'd be hungry or if it was too late, so I just bought a little of everything I could think of."

Kate hums, but her attention is shifting onto the French press atop her counter, half filled with the black liquid that she reaches for, pours into a cup. "Do you want some coffee?"

"Decaf?"

She wrinkles her nose, but nods. "Yeah, not as good, but I didn't want to be up half the night either."

"Sure, but you should have told me. I would have brought you hot chocolate instead," he quips, accepting the extra mug she hands him.

"How could I have known when it was a surprise visit?" she counters with an arch of her eyebrow, the gleam of challenge in her gaze, so much weaker than he's used to, but he smirks in response.

"Touché."

They decide to hold off on the food for now, she doesn't seem in the mood for a meal, and Castle follows her with trepidation to her sofa, watches her curl in against the arm of the furniture and cradle her coffee to her chest, desolation returning to claim her features.

He sets his cup down on the table before them and takes a seat on the middle cushion, not too far, but far enough away to give her space, to avoid any accidental touches.

"Your hand," she says suddenly, straightening in her seat, but Castle shrugs.

"It's fine," he lies, it's pounding, the heartbeat of the bruise rattling his bones. "Barely feel it."

"Liar," she mumbles, grinning at him around the rim of her cup. "Do you want some ice?"

"No, not yet," he sighs, slumping back into her sofa.

The naked bone of her ankle is within reach and he wants so badly to extend his hand, cover her talus and smooth circles into her skin with his thumb. What he would give for a simple touch, something another man threw away with what sounded like ease.

"Beckett, if Josh couldn't see that you were worth a few missed phone calls, he didn't deserve your time," he begins, earnest, but she won't meet his eyes, lowering hers to the hardwood of her coffee table.

"I didn't expect us to last," she admits, the steam from her cup slithering upwards to caress the underside of her jaw, gliding along the hollows of her cheeks. "I guess I just didn't expect for him to figure it out so quickly either."

"Figure what out?" Castle questions, propping his elbow atop the head of the sofa, angling his body towards her.

"How bad I am at this," she chuckles, rueful, but the frown lines bracketing her mouth contradict her attempt at levity. "Relationships. It had been easy in the beginning, keeping one foot out the door, but Josh wanted to dive in and I couldn't. Can't. This is about as far as I get, Castle."

Rick shakes his head. "You just need someone who understands a little better, who can wade with you in the shallows until you're ready to go deeper."

Her eyes flicker towards him, landing on his chest, lashes hiding the swirl of colors in her gaze. She's quiet for a long moment, but he's patient, allows her the seconds of contemplation she needs.

"What if it never ends?" she asks, her voice choked and her gaze trained on the middle of his sternum. "I thought - I know we have Lockwood now, but the chances of him breaking… What if this is all I ever am, Castle? What if I never find justice for my mom? What if there's never more?"

Her eyes finally rise to seek him out, desperation bleeding into her irises, tainting them with tears. He doesn't think he's ever seen her so broken, so hopeless and lost-

"What if _I'm_ never able to be more?"

"Beckett," he breathes, watching her shudder through an exhale and stretch forward with a shaking hand to reach the coffee table, abandon any hopes of consuming the rest of the beverage.

"I don't expect you to have the answers," she rasps before he can even attempt one, swiping at her dry cheeks, ensuring no tears have fallen, but her eyes haven't stopped shimmering, haven't stopped silently pleading for him to give her at least one reassurance, whether she realizes it or not. "Just-"

She looks to him, searching his face for something he doesn't know he can give, meeting his gaze with emptiness overtaking hers.

"Tell me something with certainty."

Her voice cracks, so much need weighing down her words, and it's the wrong thing to say, the worst thing he could possibly say, but it's the only thing he's certain of, one thing that he knows is solid and true.

"I love you."

Kate goes still, her entire frame unmoving and stiff, breath held hostage in her lungs, and the floodgates of his brain to mouth filter are decimated, too many words suddenly spilling free before he can stop them.

"You asked me why I kept coming back, and I told you the truth. You're my partner, Kate, and I will always have your back, but it's - it hasn't been about the books for a while now," he sighs, echoing a confession made to his mother only days earlier, curling his hands into fists to keep them from trembling. "It's about you. Always been about you."

Her silence terrifies him, has his system in a panic, and it feels so close to wonderful, so freeing, to have the words out, for her to know the truth, but he almost wishes he could have them back, cleanse her ears of the admission and wipe that startled, wide eyed look from her face.

He's afraid he just sent Kate Beckett into shock.

"And it's okay, it's really okay, if you don't feel the same," he begins to stammer, second guessing, but doing his best to revoke some of the pressure he just placed on her. Shit, how arrogant he was, thinking she would automatically feel the same, betting that the passionate work of her mouth over his, the ardent stroke of her tongue, ensured that his feelings were reciprocated. He's just brimming with dumb ideas tonight. "I wasn't trying to make you - you just asked for certainty and that is one thing I-"

"Castle," she murmurs, snapping out of her stillness and using the head of the couch beneath her hand to hoist herself to her knees on the sofa.

The hammering of his heart intensifies, thundering through his ribcage when Kate's hands drape along his cheeks, palms cradling his jaw as her body leans in. It's the second time the heat of her breath has stained his lips within the last few hours and the sensation is intoxicating, clears his mind of worry and consequence, a blissful blank the second Kate's mouth touches his.

For a moment, the gentle pressure of her lips over his, the heat of her fingertips on his skin, the tickle of her hair grazing his throat where it falls around them, is all that there is. So vastly different from their previous kiss, their first kiss, so soft and tentative and breath stealing in a completely different way. It deprives his lungs of the last of their oxygen when her mouth fits to his with more insistency, his upper lip engulfed by the pleasant burn of her mouth, the fire of her tongue laving over the tender flesh.

Castle's hands rise to her waist, sinewy muscles and sharp bones beneath his palms, soft curves and the arch of her spine when his hands travel higher. The flare of agony bleeds through his knuckles, but he ignores it in favor of cupping her face in one hand as he had outside that warehouse, embracing her body in the lace of his arm, the spread of his fingers between the wings of her shoulder blades.

Kate's lips part for breath after a few seconds, her forehead knocking into his, but Castle takes the opportunity to slip his tongue inside the cove of her mouth, his chest fluttering at the familiar sound of her moan invading his ears, drugging the rest of his senses.

Her body is alive beneath his hands, fitting in closer against him, in tune with the work of her mouth, the dance of her tongue gliding along his. And she just broke up with her boyfriend, just had to face the consequences of her mother's case all over again, just survived another near death experience with him at her side – they needed to stop, pause at least, but god, he had just told her he loved her and her response was to kiss him. And now he never wants the moment to end.

"Kate," he mumbles, squeezing the jut of her hipbone through the thin layer of her leggings. She's half in his lap, one of her knees over his thigh, her arms around his neck and her breasts grazing his chest with every ragged inhale of breath. "Beckett-"

"I'm bad at this," she rasps, her fingers in his hair, clutching as if to hold on even as the protests spill from her lips. "I'm bad at this, Castle. I'll ruin it."

Rick softens his hold on her, his arms banding around her in an embrace, coaxing the parentheses of her body to collapse around the fragment of his, folding in against him.

"Kate, if you want this, want… me, I will do whatever it takes to make this work. We don't dive in until you're ready," he promises her, combing his fingers through the loose waves of her hair. "I can love you in whatever way you need."

A breathless noise leaves her lips, something between a laugh and a whimper. "I want you. I want you, but I'm not ready, not ready to say - I can't-"

"Then don't." Her eyes are molten pools when they find his, dark and liquid with lust and desire, but outlined in hesitation. "You don't have to say anything, be anything you aren't ready for, Kate. There's no right or wrong way to do this, no timetable."

With her hands still tangled in his hair, she drags his mouth back to hers, slow and with tenderness, presses a kiss that tastes of gratitude and yearning on his tongue.

"Okay," she breathes, her nails scratching lightly at his scalp and her lashes tickling his skin as she blinks. "I don't know how we're going to do this-"

"We'll find a way."

A smile tugs her mouth upwards, a shy, beautiful thing. "Good, because I want to."

"Should probably establish some ground rules," Castle muses, brushing his untouched set of knuckles along the base of her spine, up and down, grinning when she squirms, nips at the corner of his mouth for it.

And oh wow, he has Kate Beckett in his arms, scraping her teeth along the flesh of his lips while they discuss their relationship on her couch.

"Making out on my couch probably isn't the best way to do this," she hums, no intention of stopping if the husk of mischief in her voice is any indication. "Too fast."

"Three years of foreplay, Beckett. I think we're right on track with this."

She buries a laugh in his skin, but sighs a moment later, a sound of contemplation to prelude her words. "What if we just take it day by day? I don't - I'm not sure how to navigate this, Castle. Not sure what the best approach is or how soon is too soon, if there should be any rules at all."

"No, you're right, there are no rules," he concedes. "And I think your plan is best, the day by day thing. But does this mean I have to stop kissing you? Because I'm a patient man, Kate, but I really-"

Quieting him with her mouth once more, Kate steals his words, leaves his mind empty with the fit of her lips and the touch of her tongue, and he could get used to this.

"I don't want you to stop kissing me," she mumbles, and he thinks it's the most wonderful thing she's ever said. "I don't want this to stop."

And that may be the most relieving sentence she's ever spoken to him. Part of him fears that she'll feel differently in the morning, once the adrenaline of the day, the sorrow Josh's words had left her with, has dissipated, but in this moment, she sounds sure, confident in her choice, and all he can do is place his faith in her. Just like always.

"Tell me again," she murmurs, lips brushing and noses bumping as she traces the shell of his ear with delicate fingers.

Castle dusts his lips along the bone of her cheek, tastes the salt of tears long dried still lingering on her skin, and says the words against her temple, soft but strong. Certain.

"I love you, Kate."


End file.
